Puzzles may have one or conditions that affect a player's score.
There two types of conditions. Absolute conditions must be satisfied before a player's score can be ranked. Relative conditions apply a scoring penalty or bonus, but don't prevent a score from being ranked. Relative conditions were formerly called filters.
The most common absolute conditions are:
- condition checking is disabled
- one or more open cutpoints
- an evolver solution has not met a minimum gain
When conditions of this type are not met, the score at the top of the screen is crossed out, and the score won't appear on the scoreboards. The "conditions satisfied" line appears in red, and the unsatisfied conditions are listed if you open the dropdown.
Note: it's worth restating that an unsatisfied absolute condition prevents your solution from showing on the scoreboards. Even if you have the best solution when the puzzle expires, a single open cutpoint prevents it from showing up on the scoreboards.
In Foldit, the basic score is calculated using an algorithm based on the Rosetta software suite. Puzzles may include additional relative conditions that add a bonus or subtract a penalty depending on various factors. Particularly in design puzzles, relative conditions help direct solutions toward specific goals set by the Foldit research team.
The most common conditions in design puzzles are:
- Residue IE Score
- Core Existence
- Secondary Structure
- SS Design
- Residue Count
- Ideal Loops
- HBond Network
Some non-design puzzles include a condition that rewards the formation of disulfide bridges:
- Disulfide Count
Contact map puzzles include a condition which award bonuses for matching predicted contacts.
Older Foldit design puzzles had "Layer Score" or "Layer Design" condition (then called a "filter"), which evaluated several aspects of a protein's design. These conditions have not been used in more recent puzzles, in part for performance reasons.
The typical behaviors of these conditions are described in more detail below. The conditions may vary in operation from puzzle to puzzle.
Design Puzzle ConditionsEdit
Some or all of these conditions may be found in design puzzles.
Residue IE ScoreEdit
The Residue IE (interaction energy) Score condition, found in design puzzles, typically monitors that the aromatic ring residues are scoring well. The aromatics are phenylalanine (PHE), tyrosine (TYR), and tryptophan (TRP). The condition applies a penalty if the interaction energy is too low.The segments with penalties are highlighted with red halos if the "Show" option for the condition is checked. When there's a penalty, the segment's "Segment Information" window shows the current interaction energy and the required value. In this instance, smaller the score, the better, so a negative IE score is better than a positive score. (Normally, Foldit presents scores as positive values.)
The Core Existence condition, found in design puzzles, rewards a hydrophobic core.
In symmetry puzzles, there may be two core existence conditions: "Core Existence: Monomer" and "Core Existence: Complex". The monomer condition would be condition on a non-symmetry design puzzle (these puzzles usually have "monomer" in their titles). In a symmetry puzzle, the "Complex" core existence condition rewards the "interface" between the monomer units.
The Core Exists condition was described in a 2013 blog post. In the earliest versions, the condition was called "Core Exists", and in symmetry puzzles, applied to both the monomer unit and the interface between monomers. Later symmetry puzzles have two separate "Core Existence" conditions for the monomer and the interface.
This follow-up to the 2013 blog post describes some considerations for refining the core of a monomer.
The Secondary Structure condition in a design puzzle places limits on how many residues are in a particular type secondary structure. Since helixes score well in Foldit, the Secondary Structure condition often requires that no more then 50% of residues are in a helix. This avoids designs which are mostly helixes. In several "More Sheets!" puzzles, the secondary structure condition was reversed, to require that at least 50% of residues are in sheets.
Secondary Structure DesignEdit
In design puzzles, the Secondary Structure Design condition limits which secondary structures can contain specific amino acids. This condition often disallows cysteine (CYS) entirely, while disallowing glycine, proline, and alanine in sheets and helixes.
Some Foldit design puzzles allow players to insert additional residues (segments). The Residue Count condition penalizes adds a penalty if the number of residues exceeds the stated maximum. For example, [Puzzle 1328] started with 85 residues, but allowed players to insert up to 10 additional residues.
The concept of ideal loops has been featured in recent Foldit design puzzles. The Ideal Loops condition penalizes loops between sheets or helixes if they depart too far from ideal constraints. Several new features, such as ABEGO coloring, the Rama map and the Blueprint tool are intended to help construct ideal loops. Also, puzzles with the Ideal Loops condition typically disallow use of the "rebuild" tool, in favor of the "remix" tool. A 2016 blog post contrasts remix and rebuild, and describes the new user interface features which make the remix tool easier to use manually.
Hydrogen Bond NetworkEdit
The Hydrogen Bond Network condition was described in a [2016 Foldit blog post]. The Hydrogen Bond Network condition awards hydrogen bonds that link a series of hydrophobic residues on the surface of a protein. The condition usually includes a requirement that network bonds across monomer units in a symmetry puzzle. [Puzzle 1103] included an assymetric version of the condition, which required the network to cross multiple non-identical chains in the protein.
The Disulfide Count condition is found on non-design puzzles. The condition rewards disulfide bridges. The condition is commonly used on "revisting" puzzles. When these puzzles were originally presented, there was no special reward for disulfide bridges.
The Contact Map condition is found on contact map puzzles, and awards bonuses for matching predicted contacts.
Layer Score / Layer DesignEdit
The related Layer Score and Layer Design conditions were found in earlier Foldit design puzzles. They have been dropped in more recent puzzles.
Both conditions significantly slowed down gameplay. In particular, some use of some long-running recipes became much less feasible. The ability to disable conditions in a recipe led to recipes with "layers" or "for layers" in their titles. These recipes disabled conditions during certain operations.
While the layers conditions are gone, it's still common for Foldit recipes to offer an option to disable conditions.